Impaired cell mediated immunity has been reported in several diseases of diverse etiology and as a result of treatment with certain drugs. This immune system is very complex and functional impairment can occur in one of several steps. In some patients altered cellular immunity seems to correlate with impairment in the mitogen induced lymphoblastic transformation. Such a finding is compatible with an intracellular abnormality in these cells. In other patients, anergy in vivo does not seem to correlate with lymphoblastic transformation. This suggests that other defects in the immune system are present in these patients. This might include defects in lymphokines release or primary defects in monocyte function and metabolism. The objectives of this study will be to extend observations presently underway in our laboratory on the importance of the hexosemonophosphate shunt in lymphocytic transformation, to characterize the glucose metabolism of normal monocytes and stimulated monocytes and to characterize the effects of lymphokines on the glucose metabolism of normal monocytes. Rates of glycolysis, Krebs cycle, and hexosemonophosphate shunt activity will be estimated by the yield of 14CO2 from C14-glucose substrates in monolayer cultures of monocytes. 14CO2 production will be measured continuously with an ionization chamber and vibrating reed electrometer. The glucose metabolism of lymphocytes and monocytes will be studied in patients with impaired cellular immunity and correlated with functional changes in these cells.